The Piranha Float will make algae cleaning quick and easy. With its large 4" x 2" cleaning area and extra strong magnets it will zip through the toughest of algae. Its floating inner assembly will float to the surface if disengaged for easy retrieval. This cleaning magnet is for glass and acrylic aquariums. Good for acrylic tanks 3/16" and 1/4" thick. Good for glass tanks 1/4" and 3/8" thick.